CMS32L051 User Manual |Chapter 19 Key Interrupt Function
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19.3.2 Port mode register (PMx)
When used as a key interrupt input pin (KR0~KR5), the PMCxn bit must be set to 0 and the PMxn bit
must be set to 1 respectively. In this case, the output latch of Pxn can be 0 or 1.
The PM x register is set via an 8-bit memory operation command.
After the reset signal is generated, the value of this register changes to FFH.
An internal pull-up resistor can be used in bits using a pull-up resistor select register (PU x).
For the format of the port mode registers, refer to 2.3.1 Port Mode Registers (PMxx).